JP3161061B2 - Method for producing oxymethylene copolymer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing an oxymethylene copolymer by polymerizing a mixture of trioxane and a cyclic ether in the presence of a catalyst. By adding water together with metal salts, fatty acid amides and antioxidants,
The present invention relates to a method for producing an oxymethylene copolymer having excellent moldability and excellent color tone and hydrolysis resistance.

[0002]

2. Description of the Related Art A method for obtaining an oxymethylene copolymer by polymerizing trioxane and a cyclic ether in the presence of a polymerization catalyst is known. However, the resulting oxymethylene copolymer cannot be used immediately as a molding material. In order to be put to practical use, the polymerization catalyst must first be deactivated, the unstable portion must be removed or protected, and then a stabilizer must be added to prevent further decomposition. Of these, if the catalyst is not deactivated, the polymer will undergo depolymerization, causing a significant decrease in molecular weight and formaldehyde gas having a pungent odor. On the other hand, if the removal or protection of the unstable part is insufficient, not only is it released as a formaldehyde gas having a pungent odor itself,
Formaldehyde is oxidized to formic acid, which breaks down the main chain of the polymer and causes depolymerization, generating violent formaldehyde gas with a significant decrease in molecular weight. Also,
If the content of the stabilizer is insufficient, if a part of the polymer is decomposed even once by oxidative decomposition or the like, it is decomposed in a chain by formic acid generated by the oxidation of formaldehyde generated thereby, generating a large amount of formaldehyde gas. Therefore, in order to achieve the stability of the oxymethylene copolymer practically used, the catalyst is deactivated, the unstable portion is completely removed, and a stabilizer that captures formaldehyde generated and a stabilizer that prevents oxidation are used. Is necessary (Japanese Patent Laid-Open No. 1-153711).

[0003]

However, any of the oxymethylene copolymers that have been practically used up to now are decomposed at the time of melt molding due to insufficient one of them, and the odor caused by the irritating odor causes The mold environment is deteriorating, the formaldehyde gas generated adheres to the mold, and the mold deposits are considered to be oligomerized.For this reason, frequent mold cleaning is inevitable, or the thermal stability of the molded product is low and excellent in actual use. Heat resistance could not be obtained. In particular, although many methods have been proposed to remove or protect unstable parts and to add a stabilizer, none of these methods is inadequate, and it is natural that an irritating odor is generated when molding the oxymethylene copolymer. Further, it has become common sense to provide a mold with a vent for releasing formaldehyde gas generated, and to wash the mold at regular intervals. Attempts have been made to suppress these decompositions by adding a large amount of various stabilizers, but the deterioration of the color tone of the oxymethylene copolymer cannot be avoided.

An object of the present invention is to provide an oxymethylene copolymer which is excellent in moldability and color tone, for example, by sufficiently stabilizing the oxymethylene copolymer so that there is no formaldehyde gas and mold deposit during molding. To provide a method for obtaining

[0005]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, after deactivating the catalyst after completion of the polymerization, an alkaline earth metal salt of a fatty acid, a fatty acid amide,
It has been found that by adding water together with an antioxidant, an oxymethylene copolymer having excellent moldability, color tone and excellent hydrolysis resistance can be obtained, and the present invention has been achieved.

That is, the present invention relates to a process for preparing a mixture of trioxane and a cyclic ether from a coordination compound of boron trifluoride, boron trifluoride hydrate, and an organic compound containing an oxygen atom or a sulfur atom. When producing an oxymethylene copolymer containing an oxymethylene unit and another oxyalkylene unit by polymerizing in the presence of at least one polymerization catalyst selected from the group consisting of: (A) Alkaline earth metal salt of fatty acid 0.001 to 1.0 part by weight
(B) 0.001 to 1.0 parts by weight of fatty acid amide (C) 0.001 to 1.0 parts by weight of antioxidant (D) 0.1 to 10 parts by weight of water A process for producing an oxymethylene copolymer characterized by heating in a temperature range of

Preferred compounds among the cyclic ethers used in the present invention are ethylene oxide, propylene oxide, 1,3-dioxolan, 1,3-dioxane,
1,3-dioxepane, 1,3,6-trioxocan,
Examples thereof include epichlorohydrin and phenylglycidyl ether, and particularly preferred are ethylene oxide, 1,3-dioxolan, and 1,3-dioxepane. The copolymerization amount is preferably in the range of 0.1 to 10 mol%, particularly preferably in the range of 0.2 to 6 mol%, based on the oxymethylene unit. If it is less than 0.1 mol%, the thermal stability of the obtained polymer is low, and if it is more than 10 mol%, the mechanical strength and the moldability deteriorate, which is not preferable.

The polymerization catalyst of the present invention is at least one selected from the group consisting of boron trifluoride, boron trifluoride hydrate, and a coordination compound of boron trifluoride and an organic compound containing an oxygen atom or a sulfur atom. Are used in gaseous, liquid or as a solution in a suitable organic solvent.

Among these catalysts, a coordination compound of boron trifluoride is particularly preferable.
Diethyl etherate and boron trifluoride / dibutyl etherate are preferably used.

The amount of the polymerization catalyst added is preferably in the range of 0.001 to 0.1 part by weight, particularly preferably 0.005 to 0.05 part by weight, per 100 parts by weight of trioxane.

Various devices are known for polymerizing trioxane and cyclic ether.
The present invention is not particularly limited by the apparatus, and can be applied to bulk polymerization and a polymerization reaction performed in the presence of an organic solvent such as cyclohexane.

In the bulk polymerization, since rapid solidification and heat generation occur during the polymerization, an apparatus having a strong stirring ability and capable of controlling the reaction temperature is preferably used.

The bulk polymerization apparatus of the present invention having such performance includes a kneader having a sigma-type stirring blade, a cylindrical barrel as a reaction zone, and a screw having a coaxial and a large number of interrupted peaks in the barrel. A conventional screw extruder having a pair of mutually meshing parallel screws in a long case having a heating or cooling jacket, and a mixer which operates so that the interruption portion and teeth protruding from the inner surface of the barrel are engaged. A self-cleaning type mixer having a large number of paddles on a horizontal stirring shaft and rotating with a slight clearance between the paddle surface and the inner surface of the case when the shafts are simultaneously rotated in the same direction. And the like.

In the bulk polymerization, a strong stirring capacity is required because it rapidly solidifies at the beginning of the polymerization reaction, but once it is pulverized, a large stirring capacity is not required. The process may be divided into two stages.

[0015] The bulk polymerization reaction temperature is preferably in the range of 30 to 120 ° C, particularly preferably in the range of 60 to 90 ° C.

In the early stage of the polymerization, the temperature in the polymerization reactor tends to rise due to the heat of reaction and the frictional heat due to solidification. Therefore, it is necessary to control the reaction temperature by passing cooling water through the jacket. desirable.

In the present invention, it is important that the catalyst is deactivated, but the method may be any method. For example, a method for deactivating a catalyst by bringing a crude polymer after polymerization into contact with a large amount of an aqueous solution of a basic compound such as triethylamine or sodium carbonate has long been known. Although this method is not preferable because a small amount of a basic compound causes coloring of the oxymethylene copolymer, a sufficient amount of time is required, and washing after deactivation is completely performed. Can be obtained.

As a preferred method of deactivating the catalyst of the present invention, a method of adding a hindered amine compound or a trivalent organic phosphorus compound after completion of the polymerization can be mentioned. Among them, a method of adding a hindered amine compound to deactivate the catalyst is particularly preferable.

Typical hindered amine compounds that deactivate the catalyst used in the present invention and stop the polymerization reaction include:
Bis (2,2,6,6-tetramethyl-4-piperidinyl) sebacate, bis (1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate, 1,2,3,4
-Tetrakis butanetetracarboxylate (2,2,6,6
-Tetramethyl-4-piperidinyl) ester, poly [[6- (1,1,3,3-tetramethylenebutyl) amino-1,3,5-triazine-2,4-diyl]
[(2,2,6,6-tetramethyl-4-piperidinyl) imino] hexamethylene [(2,2,6,6-tetramethyl-4-piperidinyl) imino], 1,2,2
6,6-pentamethylpiperidine, dimethyl succinate 1- (2-hydroxyethyl) -4-hydroxy-
2,2,6,6-tetramethylpiperidine polycondensate, and N, N′-bis (3-aminopropyl) ethylenediamine · 2,4-bis [N-butyl-N- (1,2,2
2,6,6-pentamethyl-4-piperidyl) amino]
-1,3,5-triazine condensate, especially bis (2,2,6,6-tetramethyl-4-piperidinyl)
Sebacate, bis (1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate, dimethyl succinate
1- (2-hydroxyethyl) -4-hydroxy-2,
2,6,6-tetramethylpiperidine polycondensate, N,
N'-bis (3-aminopropyl) ethylenediamine
2,4-bis [N-butyl-N- (1,2,2,6,6
-Pentamethyl-4-piperidyl) amino] -1,3,
5-Triazine condensates are preferred. The addition amount is 0.001 to 5 parts by weight, preferably 0.01 to 3 parts by weight, based on 100 parts by weight of the oxymethylene copolymer. 0.001
When the amount is less than 5 parts by weight, there is no effect of improving the moldability and hydrolysis resistance of the oxymethylene copolymer, and when the amount is more than 5 parts by weight, bleeding occurs or mechanical properties are deteriorated. Further, the hindered amine compound may be added as it is, or may be added after being dissolved in an organic solvent such as benzene, toluene, or cyclohexane.

The alkaline earth metal salts of fatty acids used in the present invention include acetic acid, propionic acid, lauric acid, myristic acid, palmitic acid, stearic acid, araginic acid,
Heptadecyl acid, behenic acid, oleic acid, linoleic acid, linoleic acid, ricinoleic acid, 12-hydroxystearic acid, montanic acid, magnesium salts such as dimer acid, calcium salts, strontium salts, barium salts, among which laurin Magnesium oxide, calcium laurate, magnesium stearate, magnesium behenate, calcium behenate, calcium 12-hydroxystearate, and calcium 12-hydroxystearate can be preferably used. In addition,
In light of this, steatides are used as alkaline earth metal salts of fatty acids.
Calcium phosphate, magnesium stearate, 12
-Calcium hydroxystearate, 12-hydroxy
At least one selected from magnesium stearate
The use of certain compounds is a preferred practice in the present invention.
It can be mentioned as one of the embodiments.

The amount of the alkaline earth metal salt of a fatty acid is preferably in the range of 0.001 to 1.0 part by weight, particularly 0.01 to 0.5 part by weight, based on 100 parts by weight of the crude polymer.
If the amount is less than 0.001 part by weight, the effect of improving the moldability and hydrolysis resistance of the oxymethylene copolymer is not observed, and
If the amount is more than 1.0 part by weight, bleed-out and deterioration of mechanical properties are observed, which is not preferable.

The fatty acid amide used in the present invention includes:
Examples thereof include palmitic acid amide, stearic acid amide, oleic acid amide, ethylenebisstearic acid amide, ethylenebis-12-hydroxystearic acid amide, and methylenebisstearic acid amide. Among them, ethylene bis stearamide, ethylene bis-1
2-hydroxystearic acid amide is preferred. In addition,
In the present invention, ethylene bis
Stearic acid amide, ethylene bis-12-hydroxy
At least one compound selected from stearic acid amides
Use of the product is a preferred embodiment of the present invention.
One can be mentioned.

The amount of the fatty acid amide to be added is 0.001 to 1.0 part by weight, especially 0.01 part by weight, per 100 parts by weight of the crude polymer.
When the amount is less than 0.001 part by weight, the effect of improving the moldability of the oxymethylene copolymer is not seen, and when the amount is more than 1.0 part by weight, bleed out or coloring, It is not preferable because mechanical properties are deteriorated.

Examples of the antioxidant used in the present invention include a phenolic antioxidant and an amine antioxidant. Among them, from the viewpoints of bleed phenomenon and heat stability, hindered compounds having a molecular weight of 400 or more are particularly preferred. Phenolic compounds are preferred. As a specific example, triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-
Hydroxyphenyl) propionate], pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-
4-hydroxyphenyl) propionate], 1,6-
Hexanediol-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], 2,
2-thio-diethylenebis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate],
N, N'-hexamethylenebis [3- (3,5-di-t
-Butyl-4-hydroxyphenyl) propionamide], 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl)
Benzene, 2,4-bis (n-octylthio) -6
(4-hydroxy-3,5-di-t-butylanilino)
-1,3,5-triazine, octadecyl-3- (3,
5-di-tert-butyl-4-hydroxyphenyl) propionate, 2,2-thiobis (4-methyl-6-tert-butylphenol), 3,5-di-tert-butyl-4-hydroxybenzylphosphonate- Diethyl ester,
1,3,5-tris (4-t-butyl-3-hydroxy-2,6-dimethylbenzyl) isocyanurate, 1,
1,3-tris (2-methyl-4-hydroxy-5-t
-Butylphenyl) butane, N, N'-bis [3-
(3,5-di-t-butyl-4-hydroxyphenyl)
Propionyl] hydrazine, 2-t-butyl-6-
(3′-t-butyl-5′-methyl-2′-hydroxybenzyl) -4-methylphenyl-acrylate, 3,
9-bis [2- {3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionyloxy} -1,
1-dimethylethyl] -2,4,8,10-tetraoxaspiro [5.5] undecane. Among them, triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate], pentaerythrityl-tetrakis [3- (3,
5-di-t-butyl-4-hydroxyphenyl) propionate], 1,6-hexanediol-bis [3-
(3,5-di-t-butyl-4-hydroxyphenyl)
Propionate], N, N'-hexamethylenebis [3
-(3,5-di-t-butyl-4-hydroxyphenyl) propionamide] is preferred.

The amount of the antioxidant added is 0.001 to 1.0 part by weight, especially 0.1 to 1.0 part by weight, based on the oxymethylene copolymer.
A range of 0.7 parts by weight is preferred. When the amount is less than 0.001 part by weight, the effect of improving the moldability and hydrolysis resistance of the oxymethylene copolymer is not sufficient, and when it is more than 1.0 part by weight, bleeding phenomenon and reduction in mechanical properties are observed, which is preferable. Absent.

The amount of water used in the present invention is 0.1 to 10 parts by weight, preferably 0.5 to 5 parts by weight, more preferably 1.0 to 3 parts by weight, per 100 parts by weight of the oxymethylene copolymer. Parts by weight. If the amount is less than 0.1 part by weight, the improvement effect aimed at by the oxymethylene copolymer is small, and if it is more than 10 parts by weight, no further improvement effect can be expected. Troubles such as time consuming.

Further, when another heat stabilizer is added to and blended with the oxymethylene copolymer of the present invention, the heat stability may be further improved. Such compounds include urethane compounds, pyridine derivatives, pyrrolidone derivatives, urea derivatives, triazine derivatives, hydrazine derivatives, amidine compounds, polyamide and polyamide copolymers, polyacrylamide and polyacrylamide copolymers, ethylene / vinyl alcohol copolymers. And specifically, melamine, benzoguanamine, acetoguanamine, N-methylolmelamine, N, N′-dimethylolmelamine, N, N ′, N ″ -trimethylolmelamine, dicyandiamide, nylon 6, Nylon 6/12
Copolymers, nylon 6/66/610 terpolymers, nylon 6/66/610/12 quaternary copolymers, polyacrylamide and the like are preferred. These heat stabilizers are usually added in an amount of 100 parts by weight of the oxymethylene copolymer.
0.001 to 1.0 part by weight, preferably 0.01 to 0.1 part by weight.
5 parts by weight. If the amount is less than 0.001 part by weight, the effect of addition is not exhibited. If the amount is more than 1.0 part by weight, coloring and bleeding are observed, which is not preferable.

In the composition of the present invention, fillers such as calcium carbonate, barium sulfate, clay, titanium oxide, silicon oxide, mica powder, glass beads, carbon fiber, glass and the like are provided as long as the effects of the present invention are not impaired. Reinforcing agents such as fiber, ceramic fiber, aramid fiber, potassium titanate fiber,
Coloring agents (pigments, dyes), nucleating agents, plasticizers, release agents such as polyethylene wax, conductive agents such as carbon black, light stabilizers such as benzophenone compounds and benzotriazole compounds, adhesives, lubricants And additives such as a hydrolysis resistance improver and an adhesion aid.

In the present invention, the temperature at the time of adding water together with the stabilizer and heating is preferably in the range of 100 ° C. to 260 ° C., more preferably 170 ° C. to 260 ° C.

Hereinafter, the present invention will be described by way of examples, but the present invention is not limited to these examples.

[0031]

The present invention will be described below with reference to examples. All percentages and parts in the examples are on a weight basis.

In addition, MI shown in Examples and Comparative Examples
The value, the thermal decomposition rate Kx, molding, color tone, formaldehyde odor during molding, low mold depositability, mechanical properties, and hydrolysis resistance were measured as follows.

MI value: Measured at a temperature of 190 ° C. and a load of 2160 g according to ASTM D-1238 using pellets dried in a hot air oven at 80 ° C. for 3 hours.

The thermal decomposition rate K246: K246 is 24
It means the decomposition rate when left at 6 ° C. for a certain period of time.
The mixture was allowed to stand at 246 ° C. for 40 minutes under an air flow of ml / min, and determined by the following equation.

Kx = (W0−W1) × 100 / W0 where W0 means the weight of the sample before heating, and W1 means the weight of the sample after heating. In addition, TG / DTA200 manufactured by Seiko Denshi Co., Ltd. was used as the thermobalance device.

Molding: Using an injection molding machine having a mold clamping pressure of 40 tons, a cylinder temperature of 240 ° C. and a mold temperature of 30
C. and a molding cycle of 10 seconds, an ASTM No. 1 dumbbell specimen was injection molded.

Color: 3 pieces of ASTM No. 1 dumbbell were used by SM Color Computer SM-3 manufactured by Suga Test Instruments.
The YI values were measured by stacking the sheets.

Formaldehyde odor during molding: In the above molding, the formaldehyde concentration in the molding machine hopper was measured (ppm) during 300 shot molding.

Low mold depositability: In the above molding, the occurrence of deposits on the cavity surface of the mold during 5000 shot molding was observed; ○: not generated at all △: slightly generated ×: clearly It has occurred

Mechanical properties: AS obtained by the above injection molding
ASTM D-638 using a TM1 dumbbell specimen
The tensile strength was measured according to the method.

Hydrolysis resistance: No. 1 dumbbell specified in ASTM D638 was placed in a pressure vessel filled with pure water, and heated in a hot air oven at 120 ° C.,
After a day, the dumbbell was taken out and subjected to a tensile test in the same manner as described above. The strength retention was determined by comparison with the initial value (%).

In Examples 1 to 10 and Comparative Examples 1 to 7,
Oxymethylene crude polymer (POM) produced by the following method
-1) was used.

Production of Oxymethylene Crude Polymer (POM-1) Trioxane (30 kg / h), 1, 2 was placed in a twin-screw extruder-type polymerization machine (100 mmφ, cylinder length (L) / cylinder diameter (D) = 10). 3-dioxolane (1200g
/ H), and 130 ppm of boron trifluoride diethyl etherate (2.25% benzene solution) and 750 ppm of methylal with respect to trioxane, respectively.
Continuous polymerization was performed. Polymerization requires an external jacket temperature of 45
° C, and the rotation was performed at 60 rpm. Methylal as a molecular weight regulator was dissolved in trioxane. Also, a premix zone was provided so that the 1,3-dioxolane and the catalyst solution were premixed immediately before being supplied to the kneader. 27.3 kg of polymer as white fine powder
/ H.

Examples 1 to 10 and Comparative Examples 1 to 7 A hindered amine compound was added as a 15 to 20% benzene solution to 1 kg of the crude oxymethylene polymer (POM-1) at the ratios shown in Tables 1 and 2. The mixture was stirred for 3 minutes in a Henschel mixer to deactivate the catalyst. To this, water was added together with the alkaline earth metal salt of a fatty acid, a fatty acid amide and an antioxidant shown in Tables 1 and 2, followed by mixing for 1 minute in a Henschel mixer. The mixture was heated at a temperature of 240 using a biaxial 45 mmφ extruder with a vent manufactured by Ikegai Iron Works.
The mixture was melt-extruded and kneaded at a temperature of 10 ° C. and a degree of vacuum at the vent of 10 mmHg. The resulting polymer was extruded as strands and pelletized by a cutter. After drying the pellets at 80 ° C. for 3 hours in a hot air circulating oven, the MI value and the thermal decomposition rate Kx were measured and molded, and the mechanical properties were measured. At the time of the molding, the formaldehyde odor was measured and the low mold deposit property was evaluated. Further, a hydrolysis resistance test was performed using this molded article. Tables 3 and 4 summarize these results.

[0045]

[Table 1]

[0046]

[Table 2]

HA-1: "Sanol" LS765 [manufactured by Sankyo Co., Ltd., bis (1,2,2,6,6-pentamethyl-
4-piperidinyl) sebacate] HA-2: "Tinuvin" 622LD [manufactured by Ciba Geigy, dimethyl succinate 1- (2-hydroxyethyl)]
-4-Hydroxy-2,2,6,6-tetramethylpiperidine polycondensate] HA-3: "Chimassorb" 119FL [manufactured by Ciba Geigy, N, N'-bis (3-aminopropyl) ethylenediamine.2.4 -Bis [N-butyl-N- (1,2,
2,6,6-pentamethyl-4-piperidyl) amino]
-6-chloro-1,3,5-triazine condensate] HA-4: "Sanol" LS770 [manufactured by Sankyo Co., Ltd., bis (2,2,6,6-tetramethyl-4-piperidinyl) sebacate]

MS-1: Calcium 12-hydroxystearate MS-2: Calcium stearate MS-3: Magnesium stearate MS-4: Magnesium 12-hydroxystearate MS-5: Sodium carbonate MS-6: Calcium hydroxide

AM-1: Ethylenebisstearic acid amide AM-2: Methylenebisstearic acid amide AM-3: Ethylenebis-12-hydroxystearic acid amide

AO-1: "Irganox" 245 (manufactured by Ciba-Geigy, (triethylene glycol-bis [3
-(3-t-butyl-5-methyl-4-hydroxyphenyl) propionate]] AO-2: “Irganox” 1010 [pentaerythrityl-tetrakis [3- (3,5; Ciba-Geigy)
-Di-t-butyl-4-hydroxyphenyl) propionate]] AO-3: "Irganox" 259 [1,6-hexanediol-bis [3-3,5-di-t-butyl-, manufactured by Ciba-Geigy] 4-hydroxyphenyl) propionate]]

HS-1: polyamide 6/66/610 /
12 quaternary copolymer HS-2: melamine HS-3: polyacrylamide

[0052]

[Table 3]

[0053]

[Table 4]

As is clear from Tables 3 and 4, the oxymethylene copolymer obtained by the production method of the present invention is excellent in heat stability and therefore excellent in moldability, color tone and hydrolysis resistance. I understand.

[0055]

By using the method of the present invention, oxymethylene copolymer used for a wide range of applications such as mechanical mechanism parts and electric / electronic parts can be manufactured with high quality and high productivity. .

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C08G 2/00-2/38

Claims (7)

(57) [Claims] 1. A mixture of a trioxane and a cyclic ether selected from the group consisting of boron trifluoride, boron trifluoride hydrate, and a coordination compound of boron trifluoride and an organic compound containing an oxygen atom or a sulfur atom. When producing an oxymethylene copolymer containing an oxymethylene unit and another oxyalkylene unit by polymerizing in the presence of at least one polymerization catalyst, the polymerization catalyst is deactivated after the polymerization, and then the crude polymer is added to 100 parts by weight. On the other hand, (A) an alkaline earth metal salt of a fatty acid 0.001 to 1.0
(B) 0.001 to 1.0 parts by weight of fatty acid amide (C) 0.001 to 1.0 parts by weight of antioxidant (D) 0.1 to 10 parts by weight of water A method for producing an oxymethylene copolymer, comprising heating at a temperature in the range described above. 2. The method for producing an oxymethylene copolymer according to claim 1, wherein the polymerization catalyst is deactivated by adding a hindered amine compound after completion of the polymerization. 3. The polymerization catalyst is deactivated by adding a trivalent organic phosphorus compound after completion of the polymerization.
A method for producing the oxymethylene copolymer described above. 4. A compound (E) in addition to the compounds (A) to (D).
The method for producing an oxymethylene copolymer according to claim 1, wherein 0.001 to 1.0 parts by weight of a heat stabilizer is added. 5. The method according to claim 1, wherein the heat stabilizer is melamine or nylon 6 /.
The method for producing an oxymethylene copolymer according to claim 4, which is a 66/610/612 quaternary copolymer. 6. An alkaline earth metal salt of a fatty acid (A) in an amount of 0.001 to 1.0 with respect to 100 parts by weight of the crude polymer.
Parts by weight (B) 0.001 to 1.0 parts by weight of fatty acid amide (C) 0.001 to 1.0 parts by weight of antioxidant (D) 0.1 to 10 parts by weight of water and use a mixer 2. The method for producing an oxymethylene copolymer according to claim 1, wherein the mixture is heated at a temperature not higher than the melting point of the polymer and then heated in a temperature range of 100 to 260 ° C. 7. An alkaline earth metal salt of a fatty acid (A) in an amount of 0.001 to 1.0 with respect to 100 parts by weight of the crude polymer.
Parts by weight (B) 0.001 to 1.0 parts by weight of fatty acid amide (C) 0.001 to 1.0 parts by weight of antioxidant (D) 0.1 to 10 parts by weight of water and use a mixer The method for producing an oxymethylene copolymer according to claim 1, wherein the mixture is heated and kneaded in a temperature range of 170 to 260 ° C using a twin-screw extruder with a vent.